Revenue Recognition and Valuation Accounts - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Allowance for doubtful accounts	$ 5.4		$ 5.4		$ 5.2
Allowance for contractual discounts	119.7		119.7		103.6
Allowance for uncompensated care	35.6		35.6		41.9
Value of uncompensated care to patients	2.2	$ 2.2	6.9	$ 7.0
Estimated cost of charity services	0.5	$ 0.4	1.8	$ 1.5
Inventory valuation reserves	$ 17.1		$ 17.1		$ 15.4